Crstalline cyclic organotin compounds and process of making the same



United States Patent Oflice 3,384,649 Patented May 21, 1968 3,384,649CRYSTALLINE CYCLIC ORGANOTIN COM- POUNDS AND PROCESS OF MAKING THE SAMEOtto S. Kauder, Jamaica, N.Y., assignor to Argus Chemical Corporation,Brooklyn, N.Y., a corporation of Delaware No Drawing.Continuation-impart of application Ser. No. 454,966, May 11, 1965. Thisapplication Aug. 28, 1967, Ser. No. 663,529

12 Claims. (Cl. 260-4291) ABSTRACT OF THE DISCLOSURE Cyclic crystallineorganotin compounds that are polymers of dipropyl, dibutyl or diamyl tinaromatic acid salts and a process for preparing such salts, areprovided, that comprise the structural units:

In the above formula, R is an aromatic radical, and R R R, and R arealkyl radicals having from three to five carbon atoms, x is a numberfrom about 0.7 to about 17, y is a number from 1 to about 5, and theratio x/y is within the range from about 0.7 to about 3.5.

The [--O] groups serve as linking radicals between groups may be linkedcoordinately thereto as residues of the normal salts.

This application is a continuation-in-part of Ser. No. 454,966, filedMay 11, 1965, now abandoned.

This invention relates to crystalline cyclic organotin compounds and toa process for preparing such compounds, and more particularly topolymeric dipropyltln, dibutyltin and diamyltin salts of aromatic acidsand to a process for preparing such crystalline cyclic polymeric saltsby reacting the corresponding organotin salts with organotin oxides. Theinvention also relates to halogencontaining resins stabilized with suchcompounds, to a process for stabilizing halogen-containing resins byincorporating such compounds with the resin, and also to stabilizercompositions for halogen-containing resins ineluding an organotincompound of the invention.

Organotin compounds generally are recognized stabilizers of highefficiency for halogen-containing resins such as polyvinyl chloride andcopolymers of vinyl chloride and vinyl acetate or other copolymerizablemonomers. Most of the commonly used organotin compound stabilizers areliquids. Some of these have a strong odor that cannot be entirelyovercome in the resin composition. A liquid stabilizer is diflicult tohandle under certain conditions, and in addition, when used inrelatively large proportions. may undesirably diminish the softeningtemperature of the resin. Furthermore, these tin compounds are usuallytoxic and therefore have not been used in containers for foodstuffs.This toxicity is important because of the generally high solubility oforganotin materials in organic solvents, which results in the migrationof the stabilizer into any organic material contained therein.

Two well-known organotin compounds which are solids are dibutyltin oxideand dibutyltin maleate. Although dibutyltin oxide is not readily solubleit is a poor stabilizer in halogen-containing resins. Dibutyltin maleatehas good stabilizing properties but introduces odors during processing,and tends to produce compositions which plate out on the rolls and havepoor lubricity. In many cases, the resin compositions containing thisstabilizer are brittle. The art has accordingly accepted the liquidcondition of organotin stabilizers as the optimum, and many suchstabilizers have been formulated and marketed. Furthermore, workers inthis field considered easy solubility of organotin stabilizers to bedesirable, to simplify blending and forming of resin compositions.

Organotin compounds containing tin linked to carbon in the form ofalkyl, aryl, hcteroeyclic or alicyclie groups and to oxygen in the formof carboxylate groups such as malcate, benzoate, laurate, or acetate arethe subject of many patents. US. Patent No. 2,307,157 to Quattlebaurn etal., dated Jan. 5, 1943, is a very early patent in this field, anddescribes organotin salts of alpha, beta-ethylenically unsaturatedcarboxylic acids such as dibutyltin dimaleate. Quattlebaum et al. pointout that the organotin salts of saturated carboxylic acids are lesssatisfactory than the salts of the unsaturated acids, because of adecrease in clarity in the finished resin.

Saturated acid salts of organotin bases are described in Yngve US.2,307,092, dated Jan. 5, 1943, and in US. Patent No. 2,560,034, datedJuly 10, 1951 to Eberly. Eberly also discloses the alkyltin salts ofaromatic acids such as the benzoates, heterocyclic acids such as thefuroates, and dibasic saturated acids such as the succinates andsebacates.

Mack et a]. in Patent No. 2,592,926, dated Apr. 15, 1952, point out thatwith increasing length of the carboxylic chain the compatibility oforganotin salts of the higher fatty acids is decreased. If dibutyltindilaurate is used in amounts of more than 2 to 3%, for instance, ittends to exude or sweat out, giving an oily or greasy film on thesurface. Furthermore, films prepared from such resins show a slight hazeinstead of the clarity desired.

The saturated organotin carboxylic acid salts have not, however, beenoutstanding stabilizers. Accordingly, the art proceeded to developorganotin thio acid monoester salts, such as the mercaptoalkanoic acidesters of US. Patents Nos. 2,64l,588 and No. 2,641,596, dated June 9,1953, to Leistner et al.. and US. Patent No. 2,648,650 to Weinberg et21., dated Aug. 11, 1953. These compounds are now recognized as the bestavailable organtotin stabilizers. They are, of course, liquids, but theyimpart outstanding stability to halogenated resins containing them, andthey are markedly free from undesirable side efl ects. The only problemis their odor.

Attempts have been made to develop polymeric organotin salts which areuseful stabilizers for halogen-con- 3 taining resins and which have lowvapor pressures at the high processing temperatures of the resin. Mackct al. in US. patents, No, 2,592,926 dated Apr. 15, 1952, No. 2,626,953,dated Jan. 27, i953, and No. 2,628.2l 1, dated Feb. 10,1953, describe anumber of organotin compounds derived from polymers of dialkyltinoxides. The C011.- pounds disclosed in Patent No. 2,592,926 have theforwherein R is an aliphatic, alicyclic or aryl alltoxy radical, R isthe residue of an alkyl, alicyclic or aryl radical of the (R0) group,and R and R stand for members of the group consisting of alkyl and aryl.n designates the degree of polymerization, and can be a number having avalue higher than 1.

The compounds of No. 2,626.953 have the formula:

wherein R and R are alkyl, aralkyl or alicyclic groups attached to theterminal oxygen of the central tin oxide chain through a carbon-oxygenlinkage, R and R stand for alkyl or aryl radicals, and n is any numberhigher than 1.

The polymers of No. 2,628.2ll to Mack ct al. are the esters of thepolymeric stannanctliols having the formuiu:

where R is alkyl or aryl, and n is a numeral from l to ll.

These linear polymeric stannanediols are esterified by i reaction withan aliphatic monocarboxylic or dicarboxylic saturated or unsaturatedacid. The polymeric material may also be formed by the polymerization ofthe monomeric salt, i.e.,

Naphthenic acid is referred to, and aromatic acid esters also aresuggested generally. The specific materials named or tested, however,are all linear polymers, and as such have a relatively low meltingpoint, compared to a threedimensional cage-type polymer. Furthermore,Mack et al. indicate that they want an organotin material that issoluble and therefore more easily dispersed in the resin.

The working examples of No. 2,628.2ll describe, for instance, thepreparation of dialkyltin aliphatic carboxylic acid salts of theformula:

Mack et al. could also obtain the higher polymers wherein all of the Rswere aliphatic groups and n is an integer from 2 to 10. Example 2, forinstance, describes a polymeric dibutyltin diacetate in the form of adimer, a trimcr and a heptamer solid. Example 3 describes a dibutyltindi(2-ethylhexoate) which was polymerired. However, the only crystallinecompound disclosed or suggested by Mack et al. was a diaryltin compound.All of the Clldllt'yliltl compounds were either liquids, or waxy solidsin the case of the higher polymers. The diaryltin materials are not aseffective stabilizers as are the dialkyltin compounds.

Sawyer in US. Patent No. 3,083,217 discloses di(tin) compounds havingthe general formula:

These materials represent a departure from the abovecited references inthat they lack the group common to the earlier compounds wherein eachtin atom in the molecule is joined only to carbon or to oxygen.

The problem with most of these compounds, however. is that the lowmolecular weight compounds which are more compatible with the resins areliquids or relatively low-melting solids, and the high molecular weightcompounds, which are solids and resemble the dialkyltin oxides arepoorly compatible and less effective as stabilizers than the simpledialkyltin diacylates. (See No. 2,628,211. column 3, lines 1948.) Inaddition, most of the materials that are fairly high-melting solids arenot crystalline, but are rather waxy, amorphous materials which have atleast some of the structural deficiencies of liquids, and lack thesolvent resistance of three-dimensional crystalline compounds. Althoughsome of the basic dibutyltin acetates are crystalline solids, they meltat C. or lower and are readily soluble in organic solvents.

In accordance with the invention, cyclic crystalline polymericdialkyltin salts of aromatic carboxylic acids are provided which havethe extremely useful characteristics of melting at a temperature aboveC. and are relatively insoluble in the usual organic solvents. Theseorganotin compounds are polymers of dipropyl, dibutyl or diamyl tinaromatic acid salts.

These organotin compounds comprise structural units which can berepresented as follows:

In the above formula, R is an aromatic radical, having up to aboutthirty carbon atoms, and R R R and R are alltyl radicals having fromthree to five carbon atoms, such as n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl, n-amyl isoamyl, sec-amyl, Z-methylbutyl (active" amyl) and tert-amyl.

x is a number from about 0.7 to about 17. When 2: is other than an eveninteger, it will be understood that x represents an average value of xunits in different moleeulcs.

y is a number from 1 to about 5. When is not an integer, it will beunderstood that it represents an average value for y groups in differentmolecules.

The ratio x/y is Within the range from about 0.7 to about 3.5, andpreferably from about 1 to about 3. The most preferred compounds havethe ratio x/y of from about 1.7 to about 2.5.

(when x is equal to or greater than 2y, 2 :0) z :x2y (when 2y is equalto or greater than x, 2 :0)

groups may be linked coordinately thereto as residues of the normalsalts. It will be evident that when the ratio x/ y is 4 the compound isin fact the normal salt, and when x is 0, Z2 is 0, y is 1 and z, is 1,the compound is dialkyltin oxide. Both of these compounds, of course,are outside of the scope of the compounds of the invention, asrepresented by the above.

The aromatic ring can have from 1 to 5 substituents per ring, preferablynot over 3, with the ortho positions free. Suitable substituent groupsinclude organic groups such as aliphatic, cycloaliphatic, aromatic andheterocyclic substituent groups, as well as inorganic groups such ashalogen, nitro and hydroxy. Preferably, the substituent groups are alkylgroups having up to ten carbon atoms, and aryl groups, alkaryl oraralkyl groups and condensed aryl or aralkyl groups having up totwenty-five carbon atoms each and unsaturated aliphatic groups, thegroups being connected to the ring directly or through oxygen, sulfur ornitrogen atoms. The organic substituent groups may be hydrocarbon orthey may be substituted with inert radicals such as, for example,halogen, phosphate, hydroxy, carbalkoxy, carbonyl, etc.

Typical alkyl substituents include methyl, ethyl, propyl, isopropyl,butyl, isobutyl, tertiary butyl, amyl, hexyl, heptyl, octyl, nonyl,decyl and the various isomers of each. Exemplary aryl substituentsinclude phenyl, naphthyl and phenanthryl. Exemplary alkaryl or aralkylsubstituents include o-tolyl, p-tolyl, m-tolyl, m-xylyl, p-xylyl,p-butylphenyl, p isononylphenyl, p tertiary octylphenyl,betamethylnaphthyl, alpha methylnaphthyl. Heterocyclic groups includefuryl and furfuyl and cycloaliphatic groups include cyclopentyl andcyclohexyl.

Examples of the preferred aromatic R groups include: p-tolyl,p-phenoxyphenyl, 3,4 dimethylphenyl, p-t-butylphenyl, salicyl,p-ethylphenyl, p-cresotinyl, p-chlorophenyl, p-chloroethylphenyl,p-ethylthiophenyl, p nitrophenyl, p-diphenyl, beta-naphthyl,S-ethyl-beta-naphthyl, 7-chloro-beta-naphthyl, p-propylphenylphenyl,p-4-nitrooctylphenyl, p hydroxyethylphenyl, p styrylphenyl, 7-hexyl-beta-naphthyl, p-naphthylphenyl, ppheny1thiophen' yl,p-pyridinophenyl, p-furfurylphenyl, p-thienylphenyl, p-furylphenyl,pyranlphenyl and p-indolylphenyl.

These novel polymeric salt compounds are characterized by alkyl radicalshaving three to five carbon atoms linked to the tin through carbon, andby aromatic carboxylate radicals linked to tin through the oxygen atomsof the carboxylic acid group. In addition, the tin atoms are linked in aring through oxygen and carbon atoms.

The compounds in the preferred group of this invention have a meltingpoint maximum at a degree of polymerization where x/y is in the rangebetween about 1.7 and about 2.5 and ideally where x/y equals 2.0. Thisgroup is characterized as having R, being selected from the groupconsisting of metaand para-substituted phcnyl unsubstituted in the orthoposition and beta-naphthyl groups.

This preferred group of materials has a maximum melting point where .r/yis about 2.0, that is abov 110 C., and do not soften below C. This highmelting three-dimensional crystalline material does not decrease thestructural rigidity of an unplasticized resin to which the material isadded. In addition, these materials unexpectedly have a low solubilityin organic solvents, which of course, makes them valuable for resinsused to make containers for organic materials such as liquid solvents orfoodstuffs. These preferred materials, as a result of their lowersolubility, exhibit a lower tendency to migrate and are therefore usefulas additives for resins used for the manufacture of containers for food.

The representational formula of the constituent units of the compoundsof the invention is not a structural formula, but the units shown arebelieved to be linked in a cyclic structure. The prior art polymericcompounds containing more than one tin atom, such as those of U.S.Patents Nos. 2,592,926, 2,626,953 and 2,628,211, are represented aslinear polymers made of %n0 units. It is believed, in contrast, that thecompounds of the invention are cyclic polymers.

Unlike the prior art linear polymers, the compounds of the invention arebelieved to have cyclic structures illustrated by the following possiblestructures, using polymeric dibutyltin toluate as illustrative:

1. x=2 x/ =0.5 R=@CH3 y i 21 3 R1R2R3R4 C4119 i e qiz a da e oie a ola OO O 0 Sn si'f SI I sh c@- CH3 l l i l O 0 O O Clisii Sn a ola a ola agula m-J2 19 14. x 2 'x/y 4.0

2; f O y 005 1 0 CHa\ /o==: (C iH9)2 O C -O l The exact cyclic structureis not fully understood; however, it is believed that the resonancecontribution of the aromatic acyl groups may favor the formation of aring structure which is actually a resonance hybrid of the structuresshown by the Formulae 1 to 14, above, as in an aromatic ring. Therefore,the indication of single and double carbon-oxygen bonds, and covalentand coordinate tin-oxygen bonds, are arbitrary. Such a resonatingstructure would have a high degree of stability, analogous to an arylring.

It is also possible to describe these organotin compounds by thesimplified representation shown below, omitting the R: [0} and S n isgroups, which are not always present and are not components impartingcrystallinity and the other distinctive features of the compounds of theinvention.

[die

20 R CH3 In this formula, R R R R and R x, y and x/y are as above.

The following compounds are given, using this simplified representation,as illustrative of compounds falling within the invention. It will beunderstood that these compounds can have a cyclic structure as indicatedabove, according to the values of x and y. The following simplifiedformulae merely suggest the cyclic structure of these compounds.

lti.

[ SCH;

CH I

Gun

The dialkyltin salts coming within the invention are crystalline solids,and have melting points above 90 C. within the degree of polymerizationindicated above. These compounds form needles or granular crystals,depending on the solvent from which they are crystallized.

The crystal structure is not the same as that of dialkyltin oxide,showing that these polymeric organotin salt are true compounds, and notmere mixtures of the dialkyltin aromatic acid carboxylate and dialkyltinoxide. In this respect, they differ from the higher polymers of U.S.Patent No. 2,628,211, which discloses these highermelting solids asbeing waxy or amorphous in nature, and not crystalline.

These compounds can be prepared by reaction of the correspondingaromatic acid with an excess of organotin oxide above that necessary toform the normal salt, i.e. a salt having a single tin atom per molecule,or two acid groups per tin atom, e.g. (R) Sn(OOCR Alternatively, thesenovel crystalline salts may be formed by the reaction of thecorresponding dialkyltin dihalide and aromatic acid salt in the basicmedium, e.g.

A preferred procedure is to react the normal dialkyltin aromatic acidcarboxylate salt with a dialltyltin oxide to form the polymericcrystalline salts of this invention. The reaction is carried out abovethe melting point of the dialkyltin carboxylate salt product. Thedialkyltin oxide is dissolved into the melted salt. The melt is kept atreaction temperature for between 15 and 30 minutes, and then cooleddown. The resultant product is crystalline. The reaction temperature forthe first reaction between the oxide and the acid is the same.

These compounds are excellent stabilizers for unplasticized (rigid)halogen-containing resins, because they are crystalline high-meltingsolids. Because of their high melting points, which are well above theheat de formation temperature of rigid PVC C.), they do not degrade themechanical properties of the resin below that temperature. Liquids andlow melting or amorphous solids tend to structurally weaken a resin whenpresent in high proportions.

These crystalline polymeric salts are easily formulated in powderedstabilizer formulations. They are compatible with the resins in theproportions required to elfect good stabilization, and, accordingly,give clear formulations from which the stabilizer has no tendency toexude. Their solubility in most organic solvents is unexpectedly lower,and thereby they have a far lesser tendency to be leached out from, orto migrate from, the resin when it is used for the packaging of foods orother organic materials.

These crystalline cyclic polymeric salts are added in the amount from0.5 to 10 parts by weight for 100 parts of resin, and preferably fromabout 1 to about 5 parts by weight.

The products of this invention are applicable to any polyvinyl chlorideresin. The term polyvinyl chloride as used herein is inclusive of anypolymer formed at least in part of the recurring group:

and having chlorine content in excess of 40%. In this group, the Xgroups can each be either hydrogen or chlorine, and n is the number ofsuch units in the polymer chain. In polyvinyl chloride homopolymers,each of the X groups is hydrogen. Thus, the term includes not onlypolyvinyl chloride homopolymers but also after-chlorinated polyvinylchlorides as a class, for example, those disclosed in British Patent No.893,288 and also copolymers of vinyl chloride in a major proportion andother copolymerizable monomers in a minor proportion, such as copolymersof vinyl chloride and vinyl acetate, copolymers of vinyl chloride withmaleic or fumaric acids or esters, and copolymers of vinyl chloride withstyrene. The invention also is applicable to mixtures of polyvinylchloride in a major proportion with a minor proportion of othersynthetic resins such as chlorinated polyethylene or a copolymer ofacrylonitrile, butadiene and styrene.

The invention is of particular application to the stabilization of rigidpolyvinyl chloride resin compositions, that is, resin compositions whichare formulated to Withstand high processing temperatures, of the orderof 375 F. and higher, and whose mechanical strength would be adverselyaffected by a liquid or low melting additive. However, the stabilizercompositions of the invention can be used with plasticized polyvinylchloride resin compositions of conventional formulation even thoughresistance to heat distortion is not a requisite. Conventionalplasticizers well known to those skilled in the art can be employed suchas, for example, dioctyl phthalate, octyl diphenyl phosphate andepoxidized soybean oil.

Particularly useful plasticizers are the epoxy higher esters having from20 to 150 carbon atoms. Such esters will initially have had unsaturationin the alcohol or acid portion of the molecule, which is taken up by theformation of the epoxy group.

Typical unsaturated acids are acrylic, oleic, linoleic, linolenic,erucic, ricinoleic and brassidic acids, and these may be esterified withorganic monohydric or polyhydric alcohols, the total number of carbonatoms of the acid and the alcohol being within the range stated. Typicalmonohydric alcohols include butyl alcohol, 2 ethyl hexyl alcohol, laurylalcohol, isooctyl alcohol, stearyl alcohol, and oleyl alcohol. The octylalcohols are preferred. Typical polyhydric alcohols includepentaerythritol, glycerol, ethylene glycol, 1,2 propylene glycol, 1,4butylene glycol, neopentyl alcohol, ricinoleyl alcohol, erythritol,mannitol and sorbitol. Glycerol is preferred. These alcohols may befully or partially esterified with the epoxidized acid. Also useful arethe epoxidized mixtures of higher fatty acid esters found innaturally-occurring oils such as epoxidizcd soybean oil, epoxidizedolive oil, epoxidized coconut oil, epoxidized cotton-seed oil,epoxidized tall oil fatty acid esters and epoxidized tallow. Of these,epoxidized soybean oil is preferred.

The alcohol can contain the epoxy group and have a long or short chain,and the acid can have a short or long chain, such as epoxystearylacetate, epoxystearyl stearate, glycidyl stearate, and polymerizedglycidyl methaorylate.

The polymeric crystalline salts of the invention can, if desired, beemployed in conjunction with other stabilizers for polyvinyl chlorideresins.

As supplemental stabilizers, there can be employed metal saltstabilizers of the type described in the Leistner et al. Patents Nos.2,564,646 and 2,716,092 and other patents in this field. The metal saltstabilizer is a salt of a polyvalent metal and an organic acid havingfrom six to twenty carbon atoms. The acid should be monocarboxylic, andit should not contain nitrogen atoms in the molecule. Aliphatic,aromatic, alicyclic and oxygen-containing heterocyclic monocarboxylicacids are operative, as a class. The acids may be substituted, ifdesired, with groups such as halogen, sulphur, and hydroxyl. Theoxygen-containing heterocyclic acids include oxygen and carbon in thering structure, of which alkyl-substituted furoic acids are exemplary.As exemplary of the acids there can be mentioned the following: caproicacid, capric acid, 2- ethyl hexoic acid, lauric acid, chlorocaproicacid, hydroxy capric acid, stearic acid, hydroxy stearic acid, palmiticacid, oleic acid, myristic acid, dodecyl thioether propionic acid C H-S(CH COOH, hexahydrobenzoic acid, benzoic acid, phenylacetic acid,isobutylbenzoic acid, monoethyl ester of phthalic acid, ethyl benzoicacid, isopropyl benzoic acid, ricinoleic acid, p t butylbenzoic acid, nhexyl benzoic acid, salicyclic acid, naphthoic acid, 1 naphthaleneacetic acid, orthorbenzoyl benzoic acid, naphthenic acids derived frompetroleum, abietic acid, dihydroabietic acid, and methyl furoic acid.These are used in the form of their metal salts, particularly thealkaline earth metal salts, such as magnesium, barium, strontium andcalcium, and the zinc, cadmium, lead and tin salts. Where these saltsare not known, they are made by the usual types of reaction, such as bymixing the acid, acid chloride or anhydride with the corresponding oxideor hydroxide of the metal in a liquid solvent, and heating, ifnecessary, until salt formation is complete. The barium, cadmium andzinc compounds are preferred.

Additional stabilizers which add to the heat stabilizing efliciency ofthe compounds of this invention and which particularly impart importantoxidation resistance to the resins are the phenols. The phenol compoundshave the structure:'

wherein R can be hydrogen, alkyl, aryl, alkenyl, alkaryl, aralkyl,cycloalkyl, hydrocarbon groups containing from one to thirty carbonatoms, heterocyclic sulfur containing groups, alkoxy, halogen, or acyl(R@O-), where R is aryl, alkyl or hydrogen and x and x: are integersfrom one to four, and the sum of x, and x does not exceed six.

Polycyclic phenols include groups which are linked by thio or oxyethergroups or by alkylene, alicyclene or arylene groups and are defined bythe formula:

wherein Q Q and Q are each inert substituent groups on the phenylnucleus; Z and Z are bivalent linking radicals; m is an integer fromzero to a maximum of 5(x +y,), m can be an integer from zero to threeand 111 an integer from zero to tour; 1:; can be an integer from zero toabout six and x an integer from one to five, preferably one. Preferably,the hydroxyl groups in polycyclic phenols are located ortho and/or parato Z. There can be one or more hydroxyl groups per phenyl nucleus, 1' 3'and y representing the number thereof. Preferably, there will be onlyone hydroxyl group per phenyl nucleus. The phenolic hydroxyl may beeither hindered, i.e., substituted in both positions ortho to thehydroxyl group, or partially hindered or unhindered, i.e. substituted inone or neither position.

Z can be a single bond, as in diphenyl, or a bivalent group such as:

Representative phenols include guaiaeol, resorcinol monoacetate,vanillin, butyl salicylate, 2,6 ditert-butylA- methyl, phenol, 2tert-butyl 4 methoxy phenol, 2,4- dinonyl phenol, 2,3,4.5 tctradecylphenol, tetrahydro-mnaphthol, ortho, meta and paracresol, ortho. metaand para-phenylphenoL ortho, meta and para-xylenols, the carvenois,symmetrical xylenol, thymol, ortho, meta and para-nonylphenol, ortho,meta and para-dodecyl phenol, and ortho, meta and paraoctyl phenol, oandmtert butyl-p-cresol, p-n-dccyloxy phenol, p-n-decyloxy cresol, nonyln-decyloxy cresol, eugenol, isoeugenol, glyceryl monosalicylate,methyl-p-hydroxybenzoate, ethyl p hydroxy cinnamate, 4 benzyloxyphenol,p-acetylaminophenol. p-steurylaminophenol, p-di-chlorobcnzoylaminophcnoland p-hydroxysalicyl anilide.

Exemplary polyhydric phenols are orcinol, propyl gallate. catechol,resorcinol. 4-octyl resorcinol, 4-dodecyl resorcinol, 4 octadecylcatechol, 4 isooctyl-phloroglucinol, pyrogallol, hexahydroxy benzene,4-isohexylcatecl'lol, 2.6 ditertiary-hutyl rcsorcinol, 2,6 diisopropylphloroglucinol.

Exemplary polyhydrie bisphcnols arernethylenebis(2,6-ditertiarybutyl-phcnol), 2,2bis-(4-hydroxy phenyl)propane, methylene-bis-( p-cresol 4,4-oxobis-(3-methy1-6-isopropylphenol), 2,2'-oxobis-(4-dodccyl phenol), 4,4-n-butylidenebis-(2tertiarybutyl-Smtethylphcnol 4,4-benzylidcnebis-( Z-tcrtiarybutyl-5-methylphenol 4,4cyclohexylidenebis(Z-tertiary butylphenol),4,4'thiobisphenol, 4,4'-thiobis(3-rnethyl-6tertiary-butylphenol),2,2'-thiobis(4-methyl--6tertiary-butylphenol2.2'-methylenebis(4-methyl-6-( l-methyl-cyclohexyl phenol),2,6-bist2-hydroxy-3-tertiary-butyl 5'-methylbenzyl)- 4-methylphenol,l,1,3-tris(2'-methyl-4'-hydroxy-5'-tert butylphenyl) butane.

Aromatic amines which may be added to the crystalline salts of thisinvention as supplemental stabilizers are represented by the formula:

wherein Z is an aromatic neucleus containing one or more separate orcondensed aromatic rings, such as benezene and naphthalene rings, thenitrogen atom being attached to the ring as a substituent, orconstituting a ring atom in a heterocyclic ring, which may itself besaturated or unsaturated, or even aromatic, and wherein R and R arepresent depending on the number of valences of the nitrogen unattachedto the ring. R and R can each be hydrogen or alkyl, aryl. alkaryl,aralkyl or cycloalkyl hydrocarbon groups containing from one to thirtycarbon atmos. Preferably, each of R and R contains from one to tencarbon atoms. y can be any integer from one to the maximum number ofavailable positions for substitucnts on the aromatic nucleus, usuallysix or eight per nucleus. These aromatic amine stabilizers are morefully set forth in U.S. application Ser. No. 161,769, filed on Dec. 19,1961 by Otto S. Kaudcr.

Also effective as stabilizers are organic compounds containing at leastone epoxy group. These compounds may be used to supplement the essentialstabilizers. The amount can range from 0' to parts by weight per 100parts of resin, depending upon the effect desired; as many epoxycompounds are also plasticizers for polyvinyl chloride resins, theamount to be added will depend on whether it is desired to plasticizethe resin.

Any epoxy compound can be used. The compounds can be aliphatic orcycloaliphatic in character, but aromatic, heterocyclic, and alicyclicgroups can also be present. The compounds have from 10 to carbon atoms.The longer chain aliphatic compounds of 22 carbon atoms and more arealso plasticizers. These are more fully set out in U.S. application Ser.No. 161,769 filed Dec. 19, 1961 by Kauder. Typical epoxy stabilizercompounds that are not also plasticizers include epoxy carboxylic acidssuch as epoxy stearic acid, glycidyl ethers of polyhydric alcohols andphenols, such as triglycidyl glycerine, diglycidyl ether of diethyleneglycol, glycidyl epoxy stearyl ether, 1,4bis(2,3-epoxy-propoxy) benzene,4,4-bis(2,3- epoxypropoxy) diphenyl ether, l,8-bis(2,3 epoxypropoxy)Octane, 1,4-bis(2,3-cpoxypropoxy) cyclohcxane, and 1,3- bis(4,5-epoxypentoxy) S-chlorobenzcne, the cpoxypolyethers of polyhydric phenols,obtained by reacting a poly- 29 hydric phenol with a halogen-containingepoxide or dihalohydrin, such as the reaction products of resorcinol,catechol, hydroquinone, methyl resorcinol or polynuclear phenols such as2,2'-bis(4-hydroxyphenyl) propane (Bisphenol A),2,2-bis(4-hydroxyphenyl) butane, 4,4'-dihydroxybenzophenone and1,5-dihydroxy naphthalene with halogen-containing epoxides such as3-chloro-1,2-epoxybutane, 3-chloro-l,2-epoxyoctane and epichlorhydrin.

Organic sulfides containing the nucleus in the molecule, are extremelyeffective supplemental stabilizers with the organotin materials of thisinvention. This group can be attached to other structures formingsaturated or unsaturated straight or branched open chain or carbocyclicor nonaromatic heterocyclic sulfides. The groups attached to the nucleuscan be substituted with other groups such as alkyl, aryl, carbonyl,alltoxy, aryloxy, amido, nitrile, ester, oxyether, thioether, hydroxyland halogen groups.

The preferred organic sulfides can be characterized by the formula:

in which Z Z Z and Z can each be hydrogen or an organic group containingfrom one to about thirty carbon atoms. Z and Z can be taken together asa heterocyclic ring including the sulfur. Z Z Z and Z can for example besaturated or unsaturated hydrocarbon radicals such as alkyl, alkenyl,cycloalkyl, arylalkyl and alkylarylalkyl, or radicals includingoxygenated groups and/or additional oxyand thiocar'ooxylic acid, oxyandthiocarboxylic ester, hydroxyl, amido, nitrile, oxyether, thioether, andcarbonyl groups and halogen atoms such as chlorine, bromine and iodine.

Among the solid high melting sulfur compounds which may be added fortheir heat stabilizing properties, are included thiomalic acid, which isexcellent for its good color retention and moderate odor. Other usefulsolid sulfur additives include elemental sulfur, 2-4mercapt0ben20icacid, thiodipropionic acid and thiodiacetic acid.

Another group of organic sulfur-containing compounds which are excellentsupplemental stabilizers for use with the crystalline organotincompounds of this invention are the mercapto-acid compounds. Theseinclude the aliphatic, aromatic, cycloaliphatic and heterocyclic acids,which contain at least one mercapto group, and can also contain inertsubstituents such as halogen, hydroxyl, keto and alkoxy groups, such as,for example, mervaleric acid, mercaptohexanoic acid, mercaptooctanoicleic acid, mercaptooleic acid, mercaptoricinoleic acid, mercaptostearicacid, mercaptobutyric acid, mercaptovaleric acid, mercaptohexanoic acid,mercaptooctanoic acid, thiolactic acid, mercaptolevulinic acid,mercaptolauric acid, mercaptobehenic acid, thiotartaric acid,mercaptopalmitic acid, mercaptomethylbenzoic acid, mercaptocyciohexanecarboxylic acid, mercaptofuroic acid, mercaptoglutaric acid,mercaptoazelaic acid, mercaptomalonic acid, mercaptoadipic acid,mercaptopimelic acid, mercaptosuberic acid, mercaptosebacic acid, andmercaptoterep-hthalic acid, and their metal salts, and esters thereofwith mono and polyhydric alcohols having from one to about thirty carbonatoms.

A total of from 0.5 to 10 parts by weight of the stabilizers can be usedfor each parts by weight of the resin. More stabilizer composition canbe used, but usually no better results are obtained, and therefore suchamounts are uneconomical and wasteful. Furthermore, to preserve theadvantages of using the crystalline high-melting salts of this inventionwith rigid polyvinyl chloride resins, if any liquid supplementaladditives are used they should be kept to a minimum.

A small amount, usually not more than 1.5% of a parting agent, also canbe included. Typical parting agents are the higher aliphatic acidshaving from twelve to twenty-four carbon atoms, such as stearic acid,lauric acid, palmitic acid, and myristic acid, mineral lubricating oils,1,3-butylene glycol ester of oxidized montan wax fatty acids, polyvinylstearate, polyethylene and parafiin wax.

This new solid stabilizer material can of couse be used with many of theliquid prior art additives listed above. However, it is obvious thatwhen using these liquid additives or when using plasticized resin, muchof the advantage gained in the mechanical properties of the resin by theuse of the solid stabilizer is lost or becomes unnecessary. Therefore,it is the solid additives combined with these crystalline basicorganotin salts which provide the best combination of additives.

The preparation of the stabilized composition is easily accomplished byconventional procedures. The selected stabilizer combination ordinarilyis blended with the polyvinyl chloride resin, using, for instance,plastic mixing rollers, at a temperature at which the mix is fluid andthorough blending facilitated, milling the stabilizer with the resin ona 2-roll mill at from 250 to 350 F. for a time suflicient to form ahomogeneous sheet, five minutes, usually. If desired, a plasticizer canbe added to the resin mixture any time prior to milling the mixture.After the mass is uniform, it is sheeted oil in the usual way.

Example 1 A high melting cyclic crystalline salt, bis(dibutyltin)di(p-t-butyl benzoate), was prepared by reacting dibutyltin oxide withp-tert-butyl benzoic acid at C. in the ratio of 1:1. The product was acrystalline solid which melted at about l69-l72 C. The product wasanalyzed to obtain the alkyl tin oxide content by titrating one gramsamples of the organotin compound dissolved in 25 cc. glacial aceticacid with a 2 N/lO HBr dissolved in glacial acetic acid according to theequation, for a normal salt, for example:

The titration is continued to an endpoint indicated by Crystal Violet.The results are shown in Table I. In this and the following examples R RR and R are generally the same groups unless indicated otherwise. Thedegree of polymerization is given as the ratio x/ y.

Examples 2 to 6 Dibutyltin oxide was reacted with para-toluic acid at180 C. A portion was reacted in a 1.522 molar ratio, oxide-to-acid,another portion in a 1.9:2 molar ratio, and a third in a 1:1 molarratio. Portions of dibutyltin oxide were also reacted with ortho-toluicacid in molar ratios of 3:2 and 2:1. The melting points were determinedand are also given in Table I below as Examples 2 to 6 respectively.

Examples 7 to 20 Similarly, melting points were otbained for variousother crystalline dialkyltin salts formed as described in Examples 1 to6, using the corresponding dialkyltin oxides and aromatic acids. Thematerials are set out in Table I as Examples 7 to 20, along with theirmelting points.

TABLE I Mlil'r'lING POINTS OF The unique property of the salts in themore preferred 25 coloration was noted. The color is reported in Tableill group, i.e. those having a melting point maximum at x/ y below.

TABLE 11 (omposittou A B Example 21 2 parts dibutyltiu 1.75 partsdihutyltin (11- 1.25 parts his dibutyltin dilzuirate tp-tert.butyhhenzoate di-(p-tortlsutyl beuzoato) (normal salt) (xly=2) I Color(lolor (olor Time of hosting, min;

0 olorlvss Colorless (olorlr-ss.

Pale yellow 't-ry pale yellow. Yellow. Pale yellow. ..rl0.... Yellow.Deep yPll0w.. llee yellow. Dark yellow Dar yellow. Yellow brown Yellowbrown. Yellow brown. 105 H ,s Yellow brown, Yellow hrown, nn,

wl'blai-k spot. wililack spot. L0 ttharrotlwflsuunfl. Charred 1)).

1 identified as the compound oi Example 1.

is about 2.0, is shown by comparing the melting points of Examples 2-4,7-10, 11-14 and 15-18. In each of these cases, the melting point is at amaximum when x/y is about 2.0.

Example 21 A series of plasticized formulations was prepared having thefollowing composition:

Plastic composition: Parts by Weight Geon 101 EP (homopolymcr of vinylchlo ride) 100 Dioctylphthalate 50 Wax E (1,3-butylene glycol ester ofoxidized montan wax acid) 0.25 Stabilizer 1 As shown in Table II.

The stabilizer was added in the proportions noted in Table II and wasblended with the polyvinyl chloride resin. The mixture was fused on atwo-roll mill and sheeted 01f. Samples were cut from the sheet andheated in an oven at 350 F. to determine heat stability. Samples werewithdrawn at fifteen minute intervals, and the dis- Homopolymer (Diamond450) 150 Thiomalic acid 0.3 2,6-di-tbutyl-p-cresol 0.6 Organotincompound 1 As shown in Table III.

The formulation was blended, shaped and tested as described in Example21, with the tests being run at both 350' F. and 375 F. The organotincompounds added to the base formulation are set out in Table III withthe test results.

The crystalline organotin compounds added are identified with referenceto previous examples where they are fully described.

Table III indicates the initial color of the sample and the time ittakes for a moderate color change" to appear, as well as the time forsevere discoloration to occur. By severe discoloration is meant theformation of an opaque, extremely dark or charred appearance.

Table III shows the eifectiveness as a stabilizing additive forpolyvinyl chloride resins of the crystalline organotin compounds of thisinvention at temperatures of 350 F. and 375 F. It shows the increasedstabilization obtained when the organotin compounds are added to a control sample which contained only a phenolic antioxidant and amercaptoacid compound.

Example 26 Examples 27-30 The procedure of Examples 22-25 was repeatedin blending, shaping and testing a rigid resin formulation having thefollowing composition:

Parts by weight PVC homopolymer (Diamond 450) 150 Wax E(1,3-butyleneglycol ester of oxidized montanwax acids) 0.15 1,1,3 tris(2 -methyl-4'-hydroxy-5-t-butylphenyl) butane (antioxidant) 0.15

Bis (di-n-butyltin) dilp-t-butylbenzoate) (y=l) (x 2) (Example 1) -2Supplemental stablizier As shown in Table IV.

The test results for Examples 27-30 are given in Table IV, below.

and of the corresponding crystalline cyclic polymeric organotin salt ofthis invention where x/y=2.0, were weighed into separate tared beakersand stirred with 10 ml. portions of the solvents shown in Table V,below. If the organotin compounds did not completely dissolve in thesolvent at room temperature, the mixture was warmed up for up to onehour in a steam bath. If the organotin compound did not completelydissolve after one hour of heating, the mixture was allowed to settleand the supernatant liquid was decanted ofl, and the remaining solidswere then washed with a liquid in which they were not soluble, andfinally heated and dried in an oven at 70 C. The dried solid material,still in the tared beaker, was finally weighed to determine what portionof the original material had dissolved. The solubilities of thecrystalline cyclic salt of this invention in the various solvents testedare shown in Table V as grams of compounds per hundred ml. of thesolvent and also in terms of grams of tin dissolved per hundred ml. ofsolvent.

TABLE V G. crystalline Temperature Solvent organotin eom- G. tin/required to pound dissolved] 100 In]. effect s0iu- 100 ml. solventsolvent tion, C.

Water 0. 2 0. 057 60 Methanol. 1.0 0. 285 60 Acetone l. 7 0. 485 60Isopro anol. 0. 6 0.171 60 Methy -othyl tone 6. 8 1.04 00 Hexane 7. 52.14 60 Toluene 7. 9 2. 25 60 C hloroiorin 2. 85 60 1 10 or more.

The normal organotin salt dissolved completely in all of the abovesolvents, except water, at a temperature of less than C. showing asolubility of 10 g. or more per 100 ml. of solvent. In water thesolubility was 0.2 g. per 100 ml. solvent.

As shown in Table V, above, however, the crystalline polymeric cyclicsalt of this invention is less soluble in all of the organic solventstested, with the exception of chloroform. Furthermore, the crystallinecyclic organotin salt of this invention dissolved only when the solventreached a temperature of C.

TABLE IV Time (mine) to Example Parts by reach severe No. Additivesweight Initial Color discoloration at- (ontroi None Light tan. 00 45 27Sulfur .M 0.3 120 28 Tliiomalic acid 0. 3 120 120 20 Thlodipropionlcacid 0. 3 120 30 Mercaptobenzoic acid. 0. 3 .do 00 The results of TableIV show the advantages to be sesured in increased stabilizingeffectiveness by mixing with the crystalline cyclic organotin salts ofthis invention the supplemental stabilizers disclosed above. As shown inTable IV a true synergistic interaction results in far superiorstabilizing activty.

Example 31 The solubility of the crystalline cyclic organotin salts wasdetermined and compared to the corresponding normal salt of thecrystalline material. Several one-gram samples of normal dibutyltindi(p-t-butylbenzoate) PVC homopolymer (Solvic 229) 127.5 Chlorinatedpolyethylene 22.5 Epoxidized soybean oil 7.5 2,6-di-tert butyl-pcresol0.6 Stabilizing additives 1 As shown in Table VI. The test results forExamples 32 through 34 are given in Table VI, below.

The results of Table VI show the advantages as increased stabilizingelfectiveness secured by mixing the crystalline cyclic organotin saltsof this invention with the supplemental stabilizers disclosed above. Asshown in Table VI a true synergistic interaction results in far superiorstabilizing activity.

Having regard to the foregoing disclosure, the following is claimed asthe inventive and patentable embodiments thereof:

1. A crystalline cyclic organotin salt of an aromatic carboxylic acidcharacterized by a melting point of at least 90 C., and comprisingstructural units having the formula:

wherein:

R is an aromatic radical having from six to about thirty carbon atomsand is attached to the carboxylic acid group by a carbon atom of thearomatic radical;

R R R and R are alkyl radicals having from three to five carbon atoms;

at is a number within the range from about 0.7 to about y is a numberfrom about 1 to about 5;

the ratio x/y is within the range from about 0.7 to about z =2yx/ 2, andwhen x is equal to or greater than z =x-2y, and when 2y is equal to orgreater than 2:,

2 :0; and

when 2yx=0 and x2y:0, a is equal to Z2, and

both are equal to zero.

2. The crystalline salt of claim 1 wherein R is selected from the groupconsisting of paraand meta-substituted phenyl, unsubstituted in theortho-position, and beta-naphthyl.

3. The crystalline salt of claim 2 wherein the ratio of x/y is in therange from about 1.7 to about 2.5.

4. The crystalline salt of claim 3 wherein R R R; and R are all butyl.

5. The crystalline salt of claim 3 wherein R R R and R are all propyl.

6. The crystalline salt of claim 3 wherein R R R and R are all amyl.

7. The crystalline salt of claim 3 wherein R is parasubstituted phenyl,unsubstituted in the ortho-position.

8. The crystalline salt of claim 7 wherein R is a p-alkyl substitutedphenyl unsubstituted in the ortho-position.

9. The crystalline salt of claim 7 wherein R is a phalo substitutedphenyl unsubstituted in the ortho-position.

10. The crystalline salt of claim 7 wherein R is a paryl phenyl groupunsubstituted in the ortho-position.

11. The crystalline salt of claim 3 wherein R is naphthyl.

12. A process for preparing the crystalline cyclic organotin salt ofclaim 1 comprising reacting the corresponding normal dialkyltin salt ofan aromatic carboxylic acid with a dialkyltin oxide selected from thegroup consisting of dipropyltin oxide, dibutyltin oxide, diamyltin oxideand isomers thereof.

References Cited UNITED STATES PATENTS 2,628.2il 2/1953 Mack et al.26045.75

TOBIAS E. LEVOW, Primary Examiner.

W. F. W. BELLAMY, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,384,649 May 21, 1968 Otto S. Kauder It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 2 line 58 "organtotin" should read organotin Column 3 lines 8 to13 the formula should appear as shown below:

3 1 [RO) {SnO)- R h Column 5 line 32 "furfuyl" should read furfuryl line43 "pyranlphenyl" should read pyranylphenyl Columns 11 and 12 thedefinition of the R radical should appear as shown below:

Column 19 lines 73 to 75 the lower portion of the formula should appearas shown below: i t Sn Sn R R R R Column 22 formula 10 the lower portionof the formula should appear as shown below i i, in 0 Sin Column 27 lines 20 to 10 at the end of each 1 ine of groups insert a semicolon line 31 S" should read -S-S- line 33 -CH (CH 3 -CH should read CH (CH 3CH line 57 "methyl phenol" should read methyl phenol Column 28 line 32"neucleus" should read nucleus line 33 "benezene" should read benzeneColumn 29 lines 60 to 62 "mervaleric acid, mercaptohexanoic acid,mercaptooctanoic leic acid" should read mercaptoacetic acid,mercaptopropionic acid, mercaptolinoleic acid Column 30 line 17 "couse"should read course line 51 (R) Sn- (BR), +TH0OCR should read (R) Sn-(Br) +2HOOCR Column 31 first formula, the lower portion of the formulashould appear as shown below: I I .y

n O--Sn 2 3 4 5 Columns 31 and 32 TABLE I fourth column, line 3 thereof,"144-146" should regd 14 4447 Column 34, TABLE V, in the heading to t esecond column, line 1 thereof, and in the heading to the third column,line 1 thereof, "G. each occurrence should read g. Column 35 line 1 "as"should read in Signed and sealed this 28th day of October 1969.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting OfficerCommissioner of Patents

